/*
    * Copyright 2020-2022 The OSHI Project Contributors
    * SPDX-License-Identifier: MIT
    */
   package oshi.driver.unix;
   
   import java.util.ArrayList;
   import java.util.Collections;
   import java.util.List;
  
  import oshi.annotation.concurrent.ThreadSafe;
  import oshi.util.ExecutingCommand;
  import oshi.util.ParseUtil;
  
  /**
   * Utility to query xrandr
   */
  @ThreadSafe
  public final class Xrandr {
  
      private static final String[] XRANDR_VERBOSE = { "xrandr", "--verbose" };
  
      private Xrandr() {
      }
  
      public static List<byte[]> getEdidArrays() {
          // Special handling for X commands, don't use LC_ALL
          List<String> xrandr = ExecutingCommand.runNative(XRANDR_VERBOSE, null);
          // xrandr reports edid in multiple lines. After seeing a line containing
          // EDID, read subsequent lines of hex until 256 characters are reached
          if (xrandr.isEmpty()) {
              return Collections.emptyList();
          }
          List<byte[]> displays = new ArrayList<>();
          StringBuilder sb = null;
          for (String s : xrandr) {
              if (s.contains("EDID")) {
                  sb = new StringBuilder();
              } else if (sb != null) {
                  sb.append(s.trim());
                  if (sb.length() < 256) {
                      continue;
                  }
                  String edidStr = sb.toString();
                  byte[] edid = ParseUtil.hexStringToByteArray(edidStr);
                  if (edid.length >= 128) {
                      displays.add(edid);
                  }
                  sb = null;
              }
          }
          return displays;
      }
  }